If $x \boxdot y = 7x+y$ and $x \triangleright y = x-6y$, find $5 \boxdot (0 \triangleright 3)$.
First, find $0 \triangleright 3$ $ 0 \triangleright 3 = 0-(6)(3)$ $ \hphantom{0 \triangleright 3} = -18$ Now, find $5 \boxdot -18$ $ 5 \boxdot -18 = (7)(5)-18$ $ \hphantom{5 \boxdot -18} = 17$.